Their relationship would become more centered around the future. They'd have more serious conversations about how to raise the child. Valka might be more open about her past experiences with dragons to Stoick, so they can decide how to share that part of her life with the baby. And Stoick would be more cautious in his actions, not wanting to put Valka or the unborn baby in danger.
One idea could be exploring how they prepare for the new arrival. They might start renovating their living space, like adding a new room for the baby. Stoick could be shown as overprotective, not wanting Valka to take any risks. Another could be that they share their hopes and dreams for the child. Valka might hope the baby inherits her love for dragons, while Stoick hopes for a strong future leader.
Mainly, it's Hiccup and Valka. Hiccup is the protagonist we know from the 'How to Train Your Dragon' series, always curious and eager to learn more about dragons. Valka, on the other hand, is a mysterious figure who has her own set of skills and knowledge regarding dragons. When they meet in the fanfiction, their different personalities and experiences collide, creating an interesting dynamic that drives the story forward.
Well, perhaps in the fanfiction, Hiccup is in trouble while on a dragon - riding adventure. Valka, who has been observing from afar, comes to his rescue. This leads to them spending time together, with Valka teaching Hiccup some new dragon - taming techniques she has learned during her time in isolation. They could also have heart - to - heart conversations about Hiccup's father and how Valka has missed so much of Hiccup's life.
Another theme is the exploration of mother - daughter like relationships. Even though they're not related by blood, they can develop a deep emotional bond similar to that. For example, in some fanfictions, Valka teaches Astrid about the secrets of dragons as a mother figure would.
The main characters are clearly Stoick and Hiccup. Stoick is Hiccup's father, and in this fanfiction, their encounter forms the central plot. Hiccup, as the character from the future, has likely developed and changed a great deal since Stoick last saw him.
In this fanfiction, perhaps Stoick would be amazed by how much Hiccup has grown and changed in the future. He might see all the new inventions and ways of life that Hiccup has brought to Berk. Maybe there would be a moment of pride as he realizes his son has become a great leader.
Perhaps in this fanfiction, Hiccup is out exploring on Toothless when they encounter a strange dragon behavior. Valka, who has been observing from afar, comes to their aid. She and Hiccup then work together to figure out what's wrong with the dragons. Along the way, they share stories about their individual experiences with different dragon species, and Hiccup is amazed by Valka's tales.